Corythosaurus

Corythosaurus:

This crested duckbill dinosaur appears in most books on dinosaurs . Its crest or helmet had two hollow chambers that probably helped control humidity and improved its sense of smell . It was also important in making noises . The shape of its skull and the sounds it made has been compared to that of a French horn. The crest was made mostly of upper-lip bone which grew back over the top of its skull